Sensor insertion devices and methods of use

ABSTRACT

An automatic sensor inserter is disclosed for placing a transcutaneous sensor into the skin of a living body. According to aspects of the invention, characteristics of the insertion such as sensor insertion speed may be varied by a user. In some embodiments, insertion speed may be varied by changing an amount of drive spring compression. The amount of spring compression may be selected from a continuous range of settings and/or it may be selected from a finite number of discrete settings. Methods associated with the use of the automatic inserter are also covered.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/552,072, filed Oct. 23, 2006, the disclosure of which isincorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to medical devices for monitoring analytesin a living body, such as monitoring glucose levels in people withdiabetes. More particularly, the invention relates to automatic devicesfor inserting analyte sensors into the skin of a patient.

BACKGROUND OF THE INVENTION

In recent years, people with diabetes have typically measured theirblood glucose level by lancing a fingertip or other body location todraw blood, applying the blood to a disposable test strip in a hand-heldmeter and allowing the meter and strip to perform an electrochemicaltest of the blood to determine the current glucose concentration. Suchdiscrete, in vitro testing is typically conducted at least several timesper day. Continuous in vivo glucose monitoring devices are currentlybeing developed to replace in vitro devices. Some of these continuoussystems employ a disposable, transcutaneous sensor that is inserted intothe skin to measure glucose concentrations in interstitial fluid. Aportion of the sensor protrudes from the skin and is coupled with adurable controller and transmitter unit that is attached to the skinwith adhesive. A wireless handheld unit is used in combination with theskin-mounted transmitter and sensor to receive glucose readingsperiodically, such as once a minute. Every three, five or seven days,the disposable sensor is removed and replaced with a fresh sensor whichis again coupled to the reusable controller and transmitter unit. Withthis arrangement, a person with diabetes may continuously monitor theirglucose level with the handheld unit. Detailed descriptions of such acontinuous glucose monitoring system and its use are provided in U.S.Pat. No. 6,175,752, issued to Abbott Diabetes Care Inc., formerly knownas TheraSense, Inc. on Jan. 16, 2001, which is incorporated by referenceherein in its entirety.

Transcutaneous analyte sensors may be inserted into the user's skinusing an automatic introducer or inserter device, such as thosedescribed in U.S. patent application Ser. No. 10/703,214, published Jul.8, 2004 under publication number 2004/0133164, now U.S. Pat. No.7,381,184, incorporated herein by reference in its entirety. Most sensorinserter devices described in the above published patent applicationhave two springs, one for driving an introducer sharp and a sensor intothe skin of a patient, and another for retracting the introducer sharp,leaving the sensor behind in the patient's skin. The spring arrangementsare chosen to provide an introducer sharp and sensor speed optimized toinsert the sensor into a typical patient.

SUMMARY OF THE INVENTION

According to aspects of some embodiments of the present invention, it isrecognized that a sensor introducer having variable insertion speeds,insertion forces, travel distances, accelerations and/or othercharacteristics of sensor insertion that may be adjusted for differentsituations and/or different patients may be desirable. For example, dueto physiological factors and trauma that may result from high speedautomatic insertion of an analyte sensor, there may be a need to slowdown and control the velocity of the puncturing apparatus. In othersituations, such as for patients with different skin characteristicssuch as higher than average skin thickness and/or skin density, it maybe desirable to speed up the velocity of the puncturing device.Alternatively, situations involving inserting sensors into differentlocations on a patient, such as the arm, torso or thigh, may benefitfrom the use of a single inserter or single inserter type with a sensorinsertion velocity that may be sped up or slowed down. According toother aspects of the invention, a single inserter type may be configuredto alternately insert different types of sensors and/or other devices,in which case an insertion setting may be set depending on which type ofsensor or device is currently being inserted.

According to other aspects of the invention, a sensor insertion devicemay be provided with an adjustable feature allowing a user to adjust thesensor insertion speed prior to use.

According to other aspects of the invention, a sensor insertion devicemay be provided with an adjustment feature allowing the insertion speedto be variably adjusted over a range of velocities.

According to other aspects of the invention, a sensor insertion devicemay be provided with an adjustment feature allowing the insertion speedto be selected from among a finite number of discrete settings.

According to other aspects of the invention, a sensor insertion devicemay be provided with an adjustment feature allowing the insertion speedto be adjusted by changing the amount of compression of a drive spring.In one embodiment, a spring compression may be adjusted by using a knob.In another embodiment, a spring compression may be adjusted by turning athumbwheel. In another embodiment, a spring compression may be adjustedby changing the orientation of a component of the inserter. In anotherembodiment, a spring compression may be adjusted by using one or moremagnets.

Various analytes may be monitored by sensors inserted into a patientaccording to aspects of the present invention. These analytes mayinclude, but are not limited to, lactate, acetyl choline, amylase,bilirubin, cholesterol, chorionic gonadotropin, creatine kinase (e.g.,CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growthhormones, hematocrit, hemoglobin (e.g. HbAlc), hormones, ketones,lactate, oxygen, peroxide, prostate-specific antigen, prothrombin, RNA,thyroid stimulating hormone, and troponin, in samples of body fluid.Monitoring systems may also be configured to determine the concentrationof drugs, such as, for example, antibiotics (e.g., gentamicin,vancomycin, and the like), digitoxin, digoxin, drugs of abuse,theophylline, warfarin and the like. Such analytes may be monitored inblood, interstitial fluid and other bodily fluids.

In certain embodiments, other types of sensors may be inserted into abody using an inserter constructed according to aspects of the presentinvention. Such sensors may include, but are not limited to, devices formeasuring physiologic parameters such as temperatures, pressures,respiration, pulse, movement and electrical signals, through means suchas mechanical, chemical, electrical, optical or otherwise. In additionto or instead of inserting a sensor(s) into a body, an inserterconstructed according to aspects of the present invention may insertmedicine, fluid delivery devices such as infusion sets, cannulas orneedles, or other medical devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Each of the figures diagrammatically illustrates aspects of theinvention. Of these:

FIG. 1 is a perspective view showing an exemplary embodiment of a sensorinserter and adhesive mount constructed according to aspects of thepresent invention.

FIG. 2 is a perspective view of an adhesive mount and sensor attached toa patient's skin.

FIG. 3 is a perspective view of a transmitter attached to an adhesivemount and transmitting to a handheld receiver.

FIG. 4 is an exploded perspective view of the embodiment shown in FIG.1.

FIG. 5 is a side elevation view of the embodiment shown in FIG. 1.

FIG. 6 is an end elevation view of the embodiment shown in FIG. 1.

FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6.

FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 5.

FIG. 9 is a broken away view similar to FIG. 8, showing a shuttle in aneutral position.

FIG. 10 is a broken away view similar to FIG. 8, showing a shuttle in acocked position.

FIG. 11 is a broken away view similar to FIG. 8, showing a shuttle in aninsertion position.

FIG. 12 is a cross-sectional view taken along line 12-12 in FIG. 5.

FIG. 13 is a perspective view of a transcutaneously implantable sensor.

FIG. 14A is a perspective view of a sensor introducer.

FIG. 14B is a bottom view of the introducer shown in FIG. 14A.

FIG. 15 is a perspective view of a shuttle member.

FIG. 16A is a perspective view of an alternative embodiment of a sensorinserter kit.

FIG. 16B is an exploded view of some of the components shown assembledin FIG. 16A.

FIG. 17 is a side elevation view schematically showing an alternativeembodiment of a sensor inserter.

FIG. 18A is a side elevation view schematically showing an alternativeembodiment of a sensor inserter.

FIG. 18B is a top view schematically showing the sensor inserter of FIG.18A.

FIG. 19A is a side elevation view schematically showing an alternativeembodiment of a sensor inserter.

FIG. 19B is a top view schematically showing the sensor inserter of FIG.19A.

FIG. 20A is a side elevation view schematically showing an alternativeembodiment of a sensor inserter.

FIG. 20B is a top view schematically showing the sensor inserter of FIG.20A.

Variation of the invention from that shown in the figures iscontemplated.

DETAILED DESCRIPTION

The following description focuses on several variations of the presentinvention. The variations of the invention are to be taken asnon-limiting examples. It is to be understood that the invention is notlimited to particular variation(s) set forth and may, of course, vary.Changes may be made to the invention described and equivalents may besubstituted (both presently known and future-developed) withoutdeparting from the true spirit and scope of the invention. In addition,modifications may be made to adapt a particular situation, material,composition of matter, process, process act(s) or step(s) to theobjective(s), spirit or scope of the present invention.

Referring to FIGS. 1-20, exemplary embodiments of a sensor inserterconstructed according to some aspects of the invention will bedescribed. FIG. 1 shows an overall perspective view of a sensor inserterkit 300 comprising a single-use sensor inserter 310 and a single-useadhesive mount 312 removably attached to the bottom thereof.

As an overview of the operation of this embodiment of an inserter kit300, the kit may come packaged generally as shown in FIG. 1 with asensor 314 (best seen in FIGS. 4 and 13) preloaded within inserter 310and with inserter 310 in a “cocked” state. After preparing an insertionsite on the skin, typically in the abdominal region, the patient mayremove an upper liner 316 and a lower liner 318 from adhesive mount 312to expose the bottom surface and a portion of the top surface of anadhesive tape 320 (best seen in FIG. 4) located beneath mount 312. Mount312, with inserter 310 attached, may then be applied to the patient'sskin at the insertion site. Safety lock tabs 322 may be squeezedtogether to allow actuator button 324 to be pressed causing inserter 310to fire, thereby inserting sensor 314 into the patient's skin with apredetermined velocity and force. Once sensor 314 has been inserted intothe skin, the patient may remove inserter 310 from mount 312 by pressingrelease tabs 326 on opposite sides of inserter 310 and lifting inserter310 away from mount 312

Referring to FIGS. 2 and 3, mount 312 is shown adhered to a patient'sskin 328 with sensor 314 already inserted, according to this exemplaryembodiment. Once inserter 310 is removed from mount 312, transmitter 330may be slid into place. The circuitry 442 of transmitter 330 may thenmake electrical contact with the contact pads on sensor 314 aftertransmitter 330 is fully seated on mount 312. Once initialization andsynchronization procedures are completed, electrochemical measurementsfrom sensor 314 may be sent wirelessly from transmitter 330 to aportable receiver 332, as shown in FIG. 3. Sensor 314, mount 312 andtransmitter 330 may remain in place on the patient for a predeterminedperiod, such as three, five or seven days. These components may then beremoved so that sensor 314 and mount 312 may be properly discarded. Theentire procedure above may then be repeated with a new inserter 310,sensor 314 and mount 312, reusing transmitter 330 and receiver 332.

Referring to FIG. 4, inserter kit 300 may be assembled as shown from thefollowing components: housing 334, actuator button 324, drive spring336, shuttle 338, introducer sharp 340, sensor 314, retraction spring342, inserter base 344, upper liner 316, adhesive mount 312, adhesivetape 320, and lower liner 318.

Sensor 314 may have a main surface 346 slidably mounted between U-shapedrails 348 of introducer sharp 340 and releasably retained there bysensor dimple 350 which engages introducer dimple 352. Introducer sharp340 may be mounted to face 354 of shuttle 338, such as with adhesive,heat stake or ultrasonic weld. Sensor 314 may also have a surface 356that extends orthogonally from main surface 346 and just beneath adriving surface 358 of shuttle 338 when mounted thereon (details ofthese features are better shown in FIGS. 7 and 13-15.)

Shuttle 338 may be slidably and non-rotatably constrained on base 344 byarcuate guides 360. As best seen in FIGS. 7, 12 and 15, shuttle 338 maybe generally formed by an outer ring 362 and an inner cup-shaped post364 connected by two bridges 366. Bridges 366 slide between the twoslots 368 formed between guides 360 and allow shuttle 338 to travelalong guides 360 without rotating. Retraction spring 342 may becaptivated at its outer circumference by guides 360, at its bottom bythe floor 370 of base 344, at its top by bridges 366, and/or at itsinner circumference by the outer surface of shuttle post 364. Drivespring 336 may be captivated at its bottom and outer circumference bythe inside surface of shuttle post 364, at its top by the ceiling 372inside actuator button 324, and/or at its inner circumference by stem374 depending from ceiling 372. When drive spring 336 is compressedbetween actuator button 324 and shuttle 338 it urges shuttle 338 towardsbase 344. When retraction spring 342 is compressed between shuttle 338and base 344, it urges shuttle 338 towards actuator button 324.

Actuator button 324 may be slidably received within housing 334 frombelow and reside in opening 376 at the top of housing 334 with limitedlongitudinal movement. Arms 378 on each side of actuator button 324 maytravel in channels 380 along the inside walls of housing 334, as bestseen in FIG. 8. Longitudinal movement of actuator button 324 may belimited in one direction by the base of arms 378 contacting the edge ofopening 376 at the top of housing 334, and in the other direction by thedistal ends 384 of arms 378 contacting stops 386 in channels 380. Inthis embodiment, slots 388 are provided in the top of housing 334 forease of housing manufacture and so tools may be inserted to inwardlycompress areas 378 beyond stops 386 to allow actuator button 324 to beremoved from housing 334 if needed.

When sensor 314, introducer 340, shuttle 338, retraction spring 342,drive spring 336 and actuator button 324 are assembled between base 344and housing 334 as shown in FIG. 4 and described above, housing 334 maybe snapped into place on base 344. Base 344 may be held onto housing 334by upper base barbs 390 that engage upper openings 392 in housing 334,and lower base barbs 394 (best seen in FIG. 5) that engage loweropenings 396 in housing 334. In this embodiment, slots 398 and 400 areprovided for ease of manufacture of housing 334, and base 344 isremovable from housing 334 with tools if needed.

Referring to FIG. 7, actuator button 324 may be provided with safetylock tabs 322 hingedly formed on opposite ends. Tabs 322 may be urgedfrom a relaxed outward position to a flexed inward position. When in thenormal outward position, shoulders 402 on the outer surfaces of tabs 322engage the rim 404 of opening 376 to prevent the actuator button 324from being depressed, thereby avoiding accidental firing of inserter310. Tabs 322 maybe squeezed inward just enough to clear the rim 404 ofopening 376 while pressing the actuator button 324 down to fire theinserter. Alternatively, tabs 322 may be squeezed further inward so thatbarbs 406 on the inside edges engage catches 408 located on a centerportion of actuator button 324, thereby defeating the safety lock toallow later firing by simply pressing down on the actuator button 324.In this embodiment, upwardly extending grips are provided on tabs 322for better visual indication of safety lock status and actuationcontrol.

Referring to FIG. 8, shuttle 338 may be provided with laterallyextending barbed fingers 412 which travel in channels 380 along theinside walls of housing 334. When shuttle 338 is inserted up intohousing 334 far enough in this embodiment, barbed fingers 412momentarily deflect inward and then snap outward again to catch on stops386. In this “cocked” position as shown, drive spring 336 may becompressed and urging shuttle 338 towards base 344, but barbed fingers412 catching on stops 386 prevent such travel.

Referring to FIGS. 9-11, the sequence of loading, cocking, arming,firing, and automatic retraction of exemplary inserter 310 will bedescribed. According to aspects of the invention, during productioninserters 310 may be fabricated and fully assembled by one vendor,except for sensor 314, which may be supplied and installed by a secondvendor in a sterile environment. Accordingly, inserter 310 may bemanufactured and shipped to the sensor vendor in a neutral state, asshown in FIG. 9. A hole 414 provided through the center of actuatorbutton 324 allows the sensor vendor to insert a pin (manually or byautomated machinery, not shown) through hole 414 to drive shuttle 338towards base 344 in a controlled fashion and hold it there against theforce of retraction spring 342. This will allow introducer sharp 340 tobe extended through base 344 (as shown in FIG. 11) so that sensor 314may be loaded into introducer 340. When the pin is removed, shuttle 338,introducer 340 and sensor 314 may be allowed to retract to the neutralposition. The sensor vendor may then cock the loaded inserter 310 beforeshipment by pushing another pin (not shown) from the opposite directionthrough a central hole 416 in base 344 (with mount 312 removed) untilthe pin contacts dimple 418 formed in the bottom of shuttle 338. Bypushing shuttle 338 towards actuator button 324 until barbed fingers 412clear stops 386, the inserter 310 may be cocked (as shown in FIG. 10.)

Referring to FIG. 10, inserter 310 may be received by the patient in thecocked position as shown. To use inserter 310, the patient may applymount 312 to the mounting site and may disable the safety mechanism aspreviously described, and may then push actuator button 324 against theforce of drive spring 336. As actuator button 324 travels toward base344, drive cam surfaces 420 on arms 378 contact ramped surfaces 422 ofbarbed fingers 412 and urge them inward. When fingers 412 are driveninward enough to clear stops 386, shuttle 338 may be driven by drivespring 336 with a predetermined speed and force to an insertionposition, as shown in FIG. 11.

Referring to FIG. 11, exemplary inserter 310 is shown in the insertionposition with the tail 424 of introducer sharp 340 extending throughbase 344 and mount 312 into the skin of the patient. FIG. 11 showsshuttle 338 in a fully extended position with its lower surface 426 (seeFIG. 15) bottomed out on base 344. However, in this embodiment, thelower orthogonal surface 356 of sensor 314 will contact an exposedsensor contact portion 428 (best seen in FIGS. 2 and 4) on top ofadhesive tape 320 supported from below by the patient's skin, andtherefore will typically stop traveling before reaching the fullybottomed out position shown. Tail 424 of introducer sharp 340 mayprovide rigidity and a skin piercing edge 430 for allowing the flexibletail 431 (FIG. 13) of sensor 314 to be implanted in the patient's skin.After providing this function, introducer sharp 340 may be immediatelyremoved from the patient and retracted into a safe position insidehousing 334 as retraction spring 342 (which has been compressed by thetravel of the shuttle) pushes shuttle 338 back towards actuator cap.Sensor 314 may be pulled from introducer 340 and held in place by thesensor contact portion 428 on top of adhesive tape 320 adhering toorthogonal surface 356 of sensor 314. The geometries of sensor dimple350 (FIG. 13) and mating introducer dimple 352 (FIG. 14A) may be chosento create a separation force between them that is less than the adhesionforce of tape 320 on orthogonal surface 356, but great enough to retainsensor 314 in introducer 340 during typical shipping and producthandling shock loads. Driving surface 358 beneath shuttle 338 may pressdown on top of orthogonal surface 356 to ensure good contact withadhesive tape 320 before shuttle 338 retracts within introducer 340.Barb(s) on sensor tail 431 may be employed to further anchor the sensorin its operating position.

Referring again to FIG. 9, in this embodiment retraction spring 342 willreturn shuttle 338 to the neutral position as shown after firing, butwithout sensor 314 which remains inserted in patient's skin (not stillin introducer 340 as shown here). Drive spring 336 may be designed to bestiffer than retraction spring 342 so that shuttle 338 oscillations arequickly dampened out, and so introducer sharp 340 does not return tosensor 314 or the patient to cause injury. With sensor 314 now insertedin the patient's skin, inserter 310 may be removed from mount 312 byinwardly flexing release tabs 326 on opposite sides of inserter 310 toremove latch hooks 432 (see FIG. 8) from mount channels 434 (FIG. 8) andthen lifting inserter 310 away from mount 312. Introducer sharp 340remains protected inside housing 334 during disposal of inserter 310.Transmitter 330 may now be slid into place on mount 312 as previouslydescribed.

In one embodiment, sensor 314 may be made from a 0.005 inch thick Mylarsubstrate, such as Dupont Melinex ST-505, print treated both sides, heatstabilized and bi-axially oriented. In this embodiment, main surface 346is 0.315 inches tall by 0.512 inches wide, and orthogonal surface 356 is0.374 inches wide by 0.202 inches deep. Sensor tail 431 is 0.230 incheslong by 0.023 inches wide. Semispherical sensor dimple 350 is 0.050inches wide and 0.026 inches deep. Introducer 340 is made from SUS 301medical grade stainless steel, 0.004 inches thick, having a surfaceroughness less than or equal to 0.5 micrometers. The height of the mainportion of introducer 340 is 0.614 inches, and the inside width is 0.513inches. The overall thickness of rolled rails 348 is 0.026 inches. Thelength and width of introducer tail 424 are 0.354 and 0.036 inches,respectively. The preferred angle of the sharp 340 is 21 degrees.Semispherical introducer dimple 352 has a radius of 0.024 inches. Also,in this embodiment, shuttle 338 has an average speed of at least 1meter/second, and has a momentum at its end of travel of about 2.65lb-m/sec.

In the above exemplary embodiment, housing 334, button 324, shuttle 338,base 344 and mount 312 are all injection molded from G.E. Lexan PC.Inside and outside working surfaces of arms 378 on button 324 arelubricated with Dow Corning 360 Medical Fluid. Drive spring 336 has afree length of 1.25 inches, a working length of 1.00 inch, and a ratebetween 20 and 30 pounds per inch. Retraction spring 342 has a freelength of 1.5 inches, a working length of 0.35 inches, and a ratebetween 0.15 and 0.35 pounds per inch. Adhesive tape 320 is medicalgrade acrylic adhesive on polyester film (such as Acutek 0396013) with asemi-bleached kraft liner having silicon release.

The following enhancements may be added to the inserter kit 300described above in an effort to increase the reliability of sensorinsertion. First, a sensor flap may be formed along the top edge ofsensor 314 (FIG. 13). When sensor 314 reaches the extended, deliveredposition as shown in FIG. 11, the sensor flap catches on a bottom edgeof base 344 to ensure that sensor 314 separates from introducer 340 asshuttle 338 returns upward to the retracted position. Adhesive may alsobe located on the bottom of orthogonal sensor surface 356 to ensure thatsensor 314 adheres to the sensor contact portion 428 on the top ofadhesive mount tape 320, as shown in FIG. 4.

Referring to FIGS. 16A and 16B, an alternative embodiment of inserterkit 300′ is shown. Actuator button 324′ may be made easier for elderlypatients to push by anchoring the upper end of drive spring 336 on ahousing bridge 470 instead of button 324. This option may also make theinsertion force of inserter 310 more consistent, and may allow strongerspring forces to be used if desired. Bridge 470 may span across opening376′ and divide it into two openings 472 in the top of housing 334′. Thetop portion of button 324′ may be bifurcated into two protrusions 474that each extend through an opening 472. A clearance hole (not shown)may be provided through the center of button 324′ to allow drive spring336 to pass through and secure around a post (not shown) depending fromthe bottom center of bridge 470.

Safety lock key 476 may be provided to prevent actuator button 324′ frombeing pressed until key 476 is removed. Aperture 478 may be provided inthe top center of bridge 470 for receiving boss 480 located at thebottom of key 476, thereby allowing key 476 to rotate. When key handle482 is rotated perpendicular to button protrusions 474 in the embodimentshown in FIGS. 16A and 16B, two opposing perpendicular fins 484 on key476 swing into inwardly facing slots (not shown) on the inside ofprotrusions 474 and prevent button 324′ from being actuated. When keyhandle 482 and fins 484 are rotated parallel to button protrusions 474such that fins 484 disengage therefrom, key 476 may be removed andbutton 324′ may then be actuated. Other than these modifications, thisalternative embodiment inserter kit 300′ functions the same as theembodiments previously described.

In another embodiment, less aggressive finger engagement with stops 386may be employed to provide an easier and more consistent release ofshuttle 338 by actuator button 324 or 324′. Alternatively, the abovedesigns may be modified to have a single, more centrally located shuttlerelease finger (not shown) instead of the two outboard fingers 412shown.

Referring to FIGS. 17-20, various alternative embodiments are showncomprising features which allow the sensor insertion velocity to bechanged. Referring first to FIG. 17, an inserter 500 embodiment having amicrometer style head or knob 502 is shown, similar in arrangement toinserter embodiments described above. Knob 502 may be attached to athreaded rod 504. Threaded rod 504 may be received through a threadedhole or inserted in fixed housing cross member 506. A distal end ofthreaded rod 504 may be rotatably or fixedly attached to compressionmember 508. Compression member 508 may be movable with respect tocarrier or shuttle 510 for compressing drive spring 512 therebetween.

Shuttle 510 may be provided with barbed fingers 514 for engaging stops516 within housing 518 to releasably retain shuttle 510 in a cockedposition, similar to the arrangements of embodiments described above.Inserter 500 may be provided with an actuator button (such as 324 shownin FIG. 1) for releasing barbed fingers 514 from stops 516 as alsopreviously described, allowing drive spring 512 to drive shuttle 510downward with introducer sharp and/or sensor 520 to be inserted into thepatient's skin. A return spring 522 may also be provided to retractshuttle 510 into housing 518 after sensor insertion.

The driving force, travel distance, velocity, acceleration and/or othercharacteristics of sensor insertion may be adjusted according to aspectsof the present invention. In this embodiment, the user may turn knob 502causing threaded rod 504 to rotate within the threaded hole or insert inhousing cross member 506. Turning knob 502 in one direction causes knob502, rod 504 and compression member 508 to move downward, therebyfurther compressing drive spring 512 against shuttle 510. Turning knob502 in the opposite direction reduces the compression of drive spring512. By turning knob 502 prior to firing inserter 500, a user mayincrease or decrease the insertion speed and/or other characteristics ofsensor insertion.

Knob 502, rod 504 and/or housing 518 may be provided with numbers,lines, pointers or other indicia to aid a user in setting knob 502 in adesired location. In this particular embodiment, a user may adjust knob502 prior to cocking inserter 500 to reduce the amount of force neededto turn knob 502, since drive spring 512 may not be compressed or ascompressed in an uncocked state. Alternatively, knob 502 may be turnedafter inserter 500 has been cocked. This scenario may provide the userwith feedback during adjustment, as inserter 500 may be designed toallow the user to feel more resistance in turning knob 502 as drivespring 512 is further compressed. It should be noted that in thisembodiment, a user is allowed to variably adjust an insertioncharacteristic such as insertion speed across a range of speeds byturning knob 502 through a range of positions. In one embodiment,inserter 500 is provided to a user with knob 502 set in a middle of arange so that the user may either increase or decrease the insertionspeed, or leave it at its default setting.

In an alternative embodiment (not shown), which is a variation of theembodiment shown in FIG. 17, knob 502 may be arranged so that it remainsin a fixed location while being free to turn. In this embodiment, athreaded hole or insert may be provided within either knob 502 orcompression plate 508, and threaded rod 504 may be fixed attached to theother. This arrangement may operate in a similar fashion to theembodiment shown in FIG. 17 and allow fixed housing cross member 506 tobe eliminated.

In another alternative embodiment (not shown), which is anothervariation of the embodiment shown in FIG. 17, knob 502, threaded rod 504and compression member 508 may be replaced with a housing cap thatrotatably engages with the main housing, such as with a threadedcoupling. The drive spring may be captured between the cap and shuttle510. As the cap is threaded into further engagement with the mainhousing, the drive spring is further compressed. Conversely, the cap maybe backed away from the main housing to reduce the compression of thedrive spring. As before, the compression setting of the drive spring mayaffect characteristics of sensor insertion, such as sensor deliveryspeed.

Referring now to FIGS. 18A and 18B, another alternative inserter 600embodiment is shown. Inserter 600 may include a thumbwheel 602.Thumbwheel 602 may protrude from housing 604 as shown to allow a user toeasily turn it for adjusting a parameter(s) of sensor insertion.Thumbwheel 602 may drive threaded rod 606 directly, or indirectly byrotatably engaging pinion 608. Pinion 608 or compression member 610 mayinclude a threaded hole or insert for receiving threaded rod 606. Withthis arrangement, rotation of thumbwheel 602 causes threaded rod 606 tolower or raise compression plate 610, thereby further compressing ordecompressing drive spring 612, respectively. Thumbwheel 602 and/orhousing 604 may be provided with numbers, lines, pointers or otherindicia to aid a user in setting thumbwheel 602 in a desired position. Awindow may be provided atop housing 604 to allow one or more indicia onthumbwheel 602 to be viewed. In all other respects, inserter 600 shownin FIGS. 18A and 18B may operate in a similar manner to that of inserter500 shown in FIG. 17.

Referring now to FIGS. 19A and 19B, another alternative inserter 700embodiment is shown. Inserter 700 includes a shuttle 702 that may berotated to affect compression of drive spring 704. As seen in FIG. 19A,barbed fingers 706 may engage with a first pair of stops 708 to holdshuttle 702 in a cocked position at a first height. As seen in FIG. 19B,inserter 700 may be provided with a second pair of stops 710. The secondpair of stops 710 may be located within housing 712 at a second heightwhich is lower than the first height. Inserter may be provided withprovisions to allow shuttle 702 to be rotated 90 degrees so that barbedfingers 706 may engage with either the first pair of stops 708 or thesecond pair of stops 710 when shuttle 702 is cocked. In this embodiment,when barbed fingers 706 are engaged with the higher first pair of stops708 as shown in FIGS. 19A and 19B, drive spring 704 is compressed morethan when barbed fingers 706 are engaged with the lower second pair ofstops 710, which may result in a higher sensor velocity when inserter700 is actuated. It should be noted that this embodiment may provide theuser with individual, discrete adjustment settings as opposed to acontinuously variable range of settings as may be provided with thepreviously described embodiments.

In alternative embodiments (not shown), more than two pairs of stops maybe provided to provide additional positions of drive spring compression.Such arrangements may be used with square, round or other shapes ofhousings. In other embodiments, one pair of stops 708 may be provided onhousing 712, and multiple pairs of barbed fingers 706 may be located atdifferent heights on shuttle 702 for alternating engagement with thepair of stops 708. Alternatively or in conjunction with this embodiment,stop(s) 708 may be located on shuttle 702 while barbed finger(s) 706 maybe located on housing 712. Other variations of these embodiments mayoccur to those skilled in the art without departing from the scope ofthe present invention.

Referring now to FIGS. 20A and 20B, another alternative inserter 800embodiment is shown. Inserter 800 includes at least one magnet 802 whichmay affect the compression of drive spring 804. Drive spring 804 may belocated between shuttle 806 and a top portion 808 of housing 810.Shuttle 806 may include a ferrous material and/or one or more magnets(not shown) for attracting shuttle 806 to magnet 802. Magnet 802 may belocated above shuttle 806 on pivot arm 812, which may pivot about hinge814. In this embodiment, a magnetic attraction between magnet 802 andshuttle 806 compresses drive spring 804 and holds shuttle 806 in acocked position. Pressing on firing tab 816 causes arm 812 to pivotabout hinge 814 in the direction shown by Arrow A and raises magnet 802away from shuttle 806. The increased separation between magnet 802 andshuttle 806 decreases the magnetic attraction between the two until theforce of compressed drive spring 804 exceeds the force of magneticattraction. At this point, drive spring 804 is allowed to extend, firingsensor 818 into the user's skin.

The degree of magnetic attraction between shuttle 806 and magnet(s) 802may be varied by the size, number, location and/or polarity of magnet(s)802. For example, a user may place additional magnets 802 on top ofpivot arm 812 to further compress drive spring 804. This in turn mayprovide a higher sensor insertion velocity. In alternative embodiments,magnet(s) may be used in conjunction with previously describedembodiments to affect spring compression. In such embodiments, no magnetmay be used for a low speed setting, and one or more magnets may be usedfor higher speed setting(s).

In other embodiments (not shown), separate cartridges may alternately beinstalled by a user, each cartridge having a different spring rate forproviding different insertion characteristics. Alternatively, a wind-uptype constant force spring may be utilized to vary the spring force.Such an arrangement may also use a ratchet and lock type mechanism toaffect the winding. In yet other embodiments, internal dampeners orother features may be used to allow adjustment of the firingcharacteristics of the inserter. For example, air bladders, movablewalls or contact areas can be employed to increase, decrease or removefriction, thereby allowing sensor shuttle speed to be varied.

In the embodiments described above, a force or forces to drive a sensoror other object into a body may come from a compression spring, anextension spring, a torsion spring, a pneumatic or hydraulic cylinder orbladder, a magnet, an electromagnet or other prime mover or device forstoring potential energy known to those skilled in the art.

In the embodiments described above, the entire insertion device orportions thereof can be either disposable or reusable.

As for additional details pertinent to the present invention, materialsand manufacturing techniques may be employed as within the level ofthose with skill in the relevant art. The same may hold true withrespect to method-based aspects of the invention in terms of additionalacts commonly or logically employed. Also, it is contemplated that anyoptional feature of the inventive variations described may be set forthand claimed independently, or in combination with any one or more of thefeatures described herein. Likewise, reference to a singular item,includes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a,” “and,” “said,” and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The breadth of the present invention is not to be limited bythe subject specification, but rather only by the plain meaning of theclaim terms employed.

1-20. (canceled)
 21. A sensor insertion device, comprising: a shuttlemovable between a first position and a second position, the shuttleconfigured to retain a transcutaneous sensor while in the first positionand release the sensor while in the second position; a drive mechanismcoupled to the shuttle to drive the shuttle from the first position tothe second position based on a first driving force, wherein the drivemechanism includes a torsion spring configured to apply the firstdriving force; a retraction mechanism coupled to the shuttle to drivethe shuttle from the second position to a neutral position based on asecond driving force, wherein the retraction mechanism includes acompression spring configured to apply the second driving force, andwherein the neutral position is between the first position and thesecond position; and a control mechanism operatively coupled to thedrive mechanism, wherein the control mechanism is configured to bemanually operated by a user, and to cause the drive mechanism to releasepotential energy stored in the torsion spring and apply the firstdriving force to the shuttle.
 22. The insertion device of claim 21,wherein the control mechanism is further configured to vary the firstdriving force over a continuous range of settings.
 23. The insertiondevice of claim 21, wherein the control mechanism is configured toalternately set the first driving force to one of a plurality ofdiscrete settings.
 24. The insertion device of claim 21, wherein thecontrol mechanism is solely mechanical.
 25. The insertion device ofclaim 24, wherein the control mechanism includes a knob configured to betwisted by the user of the insertion device such that twisting of theknob varies the first driving force of the torsion spring.
 26. Theinsertion device of claim 24, wherein the control mechanism includes athumbwheel configured to be turned by the user of the insertion devicesuch that turning of the thumbwheel varies the first driving force ofthe torsion spring.
 27. The insertion device of claim 24, wherein thecontrol mechanism includes a threaded rod.
 28. The insertion device ofclaim 21, wherein the control mechanism includes a component configuredto be set to one of a plurality of discrete, alternate shuttleorientations by the user of the insertion device, wherein each shuttleorientation varies the first driving force of the torsion spring. 29.The insertion device of claim 21, wherein the control mechanism includesa ratchet and lock mechanism.
 30. A method of inserting a sensor, themethod comprising: manually winding a control mechanism on an insertiondevice to vary a load on a torsion spring while maintaining a shuttle ofthe insertion device in a stationary position, wherein the controlmechanism includes a ratchet and lock mechanism; placing the insertiondevice against a skin layer; firing a sensor into the skin layer usingthe control mechanism by releasing potential energy stored in thetorsion spring; releasing the sensor from the shuttle of the insertiondevice; and retracting the shuttle of the insertion device to a locationwithin the insertion device by releasing potential energy stored in acompression spring.
 31. The method of claim 30, wherein manually windingthe control mechanism on the insertion device is performed beforeplacing the insertion device against the skin layer.
 32. The method ofclaim 30, wherein firing the sensor into the skin layer using thecontrol mechanism comprises depressing an actuator button.
 33. Themethod of claim 32, further comprising manually deactivating a safetymechanism before depressing the actuator button.
 34. The method of claim30, wherein firing the sensor into the skin layer using the controlmechanism further comprises displacing the control mechanism to one of aplurality of discrete settings.
 35. The method of claim 30, wherein thecontrol mechanism is solely mechanical.
 36. The insertion device ofclaim 35, wherein the control mechanism includes a knob configured to betwisted by the user of the insertion device such that twisting of theknob varies the load on the torsion spring.
 37. The insertion device ofclaim 35, wherein the control mechanism includes a thumbwheel configuredto be turned by the user of the insertion device such that turning ofthe thumbwheel varies the load on the torsion spring.
 38. The insertiondevice of claim 35, wherein the control mechanism includes a threadedrod.